Lead screw nut construction for lathes and the like



7 March 23, 1948. D. w. STRCIJM INVENTOR.

(Iii/arrays March 23, 1948.

D. w. STROM LEAD SCREW NUT CONSTRUCTION FOR LATHES AND THE LIKE 2 Sheets-Sheet 2 Filed June 11, 1945 Patented Mar. 23., 1948' orncr: 1

LEAD SCREW NUT CONSTRUCTION FOR LATHES AND THE LIKE David W. Strom, Elmira, N. Y., assignor to Hardinge Brothers, Inc., Elmira, N. Y.

Application June 11, 1945-, Serial No. 598,761

This invention relates to improvements in lead screw nuts for use on machines, such for example as lathes.

In machines employing lead screws as heretofore constructed, the two half nuts which are movable into and out of engagement with a lead screw have generally been made integral-with the jaws or parts which move toward and from the lead screw. If these nuts become worn or broken so that they must be replaced, it is a difficult operation to remove them and provide new half nuts, and-since highly skilled mechanics are required to apply these half nuts to a machine of this type, it has heretofore been common practice to send the machine back to the manufacturer for applying new lead screw half nuts thereto.

One of the objects of this invention is to provide a lead screw nut construction by means of which the half nuts which cooperate with the lead screw are readily removable and replaceable from a machine on which they are used. A further object of this invention is to provide a pair of half nuts which are so constructed that they may easily be positioned in correct relation to the jaws which move toward and from the lead screw and to the lead screw itself. It is also an object of this invention to provide improved attaching and positioning means by means of which the half nuts may be accurately positioned with reference to the lead screw and may be securely attached to the movable jaws. Other objects and advantages of this invention will appear from the following description and claims.

In the accompanying drawings, I have illustrated my invention as applied to a lathe, but it will be understood that this invention may be applied to any'othe'r type of machine in which a lead screw is employed. In these drawings:

Fig. 1 is a cross sectional elevation of a lathe apron having half nuts embodying this invention applied thereto, and the adjacent portion of the lathe bed, the section being taken in part on line I'I,Fig.3. j J v Fig. 2 is "a" fragmentary sectional elevation thereof on line 2--2,Fig. 1.

Fig. 3 is a sectional elevation thereof, on line 33, Fig. l.

Fig. 4 is a fragmentary sectional elevation thereof similar to Fig. 3 and showing one of the half nuts in released position ready to be removed 15 Claims. (Cl. i l-424.8)

shown in the accompanying drawings, and I3 represents an apron which is secured to the carriage and extends downwardly from the carriage. This apron, in the construction shown, includes a guide member l4 which is provided with a vertical guideway I5 of any suitable or usual type on which the half nuts of lathes as heretofore constructed were movable vertically toward and from each other into and out of engagement with the'lead screw 16 of the lathe. Inmy improved construction, I provide upper and lower jaw members It and I9 having guide portions formed to cooperate with the guideway I5 and which maybe moved toward and from each other by any suitable means, such for example as heretofore commonly employed. For example, each jaw may be provided with posts or pins 2, the ends of which extend into eccentric slots 2l formed in a disk 22. This disk may be pinned or otherwise secured to a collar or enlargement 24 formed on the shaft 25, 'journalled' in a plate 21 whichis rigidly secured to the guideway member M. A handle 26 is secured to the. shaft 25 for turning the .eccentrically slotted disk 22. The plate 21 secures the disk 22 and the collar 24 in a suitable circular aperture 28 formed in the guideway member 14. Any other means for moving the jaws l8 and I9 toward and from each other may be employed, if desired.

In place of forming the threads for engagement with the lead screw 16 on the semi-cylindrical faces of the jaw members l8 and I9, as was heretofore customary, I provide two or more nutsegments, for example, a pair of such segments or half nuts 30 and 3! which are removably mounted in the jaw members 18 and IQ for accurate and correct engagement with the screw threads of the lead screw I6. Any suitable or desired means for accurately positioning and securing the half nuts on the jaw members may be provided. In the construction shown by way of example for positioning the half nuts on the jaws, I provide the half nuts with convex surfaces which are partly cylindrical and which are formed to seat against corresponding cylindrical concave or recessed stir faces on'the jaws l8 andl9. The half nuts are also provided with projections or collars 36 extending circumferentially and outwardly beyond the cylindrical surfaces'35 and whichare accuratelyformed to fit into corresponding recesses or grooves 36a formed in the jaws l8 and I9. The collars 36 and the grooves into which they fit position the half nutslengthwise of the jaws l8 and I9 and, if desired, suitable means may be employed for accurately positioning the half nuts laterally of the jaws. For example, a key or projection 31 may be provided on each of the jaws l8 and IQ, for example, on clamping members 40, slidably mounted on the jaws, which may fit into a keyway or slot 38, which is formed in each half nut- This key' and its. keyway, the collars. 36 and their re-.

moved and replaced from the machine without the aid of any skilled mechanics.

The term half nut is herein used to designate any nut segment, whether the same be a half nut or less than a half nut.

I claim as my invention: I

1. In a machine having a lead screw, a pair of jaws movable toward and from said lead screw, and a pair of half nuts formed to be releasably secured to said jaws, that improvement which includes cooperating parts on said jaws and said half nuts for positioning said half nuts on said jaws and including collars on said half nuts and grooves in said jaws formed to receive said collars to hold said half nuts in correct relation to each other, to said jaws and to said lead screw, interengaging means on said jaws and said half nuts for holding said half nuts against movement about the axis of said lead screws,and gripping means for releasably securing said half nuts to said jaws. v

2. In a machine having a lead screw, a pair of jaws movable toward and from said lead screw,

and a pair of half nuts formed to be releasably secured to said jaws, that improvement which includes cooperating parts on said jaws and said half nuts for positioning said half nuts on said jaws and including collars-on said half nuts and grooves in said jaws formed to receive said collars to hold said half nuts in correct relation to each other, to said jaws and to said lead screw, and grippingmeans slidably mounted on said jaws and engaging opposite faces of said collars for releasably securing said half nuts on said aws.

3. A lead screw nut construction including a pair of jaws movable toward and from said lead screw and having grooves formed on the inner faces thereof, a pair of half nuts formed to be releasably secured to said jaws, cooperating parts on said jaws and said half nuts for positioning said half nuts on said jaws and including collars on said half nuts formed to extend into said grooves in said jaws to hold said half nuts in correct relation to each other, to said jaws and to said lead screw, undercut faces on said collars, and gripping means formed to engage said undercut faces to releasably secure said half nuts to said jaws.

4. A lead screw nut construction including a pair of jaws movable toward and from said lead screw, a pair of half nuts formed to be releasably secured to said jaws, cooperating parts on said jaws and said half nuts for positioning said half nuts on said jaws and including collars on said half nuts and grooves in said jaws formed to receive said collars to hold said half nuts in correct relation to each other, to said jaws and to said lead screw, undercut faces on said collars, and a pair of gripping members slidably mounted on said jaws and movable into engagement with said undercut faces for releasably securing said half nuts to said jaws and for drawing said half nuts toward said jaws.

5. In a lead screw nut construction for a machine having a pair of jaws movable toward and from said lead screw, that improvement which includes recesses in the faces of said jaws adjacent to said lead screw, a pair of half nuts formed to be seated in said recesses in said jaws in correct relation to each other and to said lead screw, and gripping means slidably mounted on the inner faces of said jaws for gripping said half nuts for releasably securing said half nuts to said jaws.

6. A lead screw nut construction including a 7. A lead screw nut construction, including a pair of jaws movable toward and from said lead screw and having the faces thereof adjacent to said lead screw recessed, a pair of half nuts formed to be seatedin the recesses of said jaws in operative relation toeach other and to said lead screw, said jaws having undercut guide grooves extending substantially parallel to-said lead screw, gripping members slidable in said guidegrooves for movement into and out of gripping engagement with said half nuts for holding said half nuts on said jaws, and means operable from an end of each guide groove for moving said gripping members into and'out of positloris to grip said half nuts. I p

8. A lead screwnut construction, including a pair of jaws movable toward and from said lead screw and having the faces thereof adjacent to said lead screw recessed, a pair of 'half nuts formed to be seated in the'recesses of said jaws in operative relation to each other and to said lead screw, said jaws having undercut guide grooves extending substantially parallel'to said lead screw, a pairof gripping members slidable in each guidegroove formovem'ent into and out of grippingengagement with the adjacent half nut, and a screw engaging the two gripping members of a guide groove and extending into position to be actuated from an end of said guide groove.

9. In a lathe having a lead screw and a pair of jaws constructed for simultaneous movement toward and from the lead screw, that improvement which includes a pair of half nuts formed to be releasably secured to said jaws with the half nuts positioned to cooperate with the threads of the lead screw when the jaws are moved toward each other, said jaws and nuts being formed so that when said nuts are released from said jaws, they may move lengthwise of said lead screw clear of said jaws by relative rotation of said nuts and lead screw.

10. In a machine having a lead screw, a pair of jaws movable toward and from said lead screw and a pair of half nuts carried by said jaws, that improvement which includes recesses in the inner faces of said jaws intermediate of the ends thereof, projections on said half nuts formed to extend into said recesses, and gripping means mounted on said jaws movable into and out of engagement with said projections for securing said half nuts to said jaws.

11. In a machine having a lead screw, a pair of jaws movable toward and from said lead screw and a pair of half nuts carried by said jaws, that improvement which includes recesses in the inner faces of said jaws intermediate of the ends thereof, projections on said half nuts formed to extend into said recesses, and a pair of gripping members slidably mounted on each of said jaws for movement toward and from opposite sides of said projections for releasably securing said half nuts to said jaws.

12. A lead screw nut construction including a 

